CVE-2025-28172
📋 TL;DR
Grandstream UCM6510 PBX systems running firmware v1.0.20.52 and earlier lack rate limiting on authentication attempts, allowing attackers to brute force credentials. This affects all organizations using vulnerable UCM6510 devices for VoIP communications. Attackers can gain unauthorized access to administrative or user accounts.
💻 Affected Systems
- Grandstream UCM6510
📦 What is this software?
Ucm6510 Firmware by Grandstream
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of PBX system leading to call interception, toll fraud, data exfiltration, and lateral movement into connected networks.
Likely Case
Unauthorized access to administrative interface enabling configuration changes, call routing manipulation, and potential credential harvesting from other accounts.
If Mitigated
Failed login attempts logged but no successful compromise if strong passwords and network segmentation are implemented.
🎯 Exploit Status
Simple brute force tools like Hydra or Burp Suite can exploit this. No authentication required to attempt login.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v1.0.20.53 or later
Vendor Advisory: http://grandstream.com/support/security-advisories
Restart Required: Yes
Instructions:
1. Download latest firmware from Grandstream support portal. 2. Log into UCM6510 web interface. 3. Navigate to Maintenance > Upgrade. 4. Upload firmware file and click Upgrade. 5. Wait for automatic reboot.
🔧 Temporary Workarounds
Network-based rate limiting
allImplement rate limiting at network perimeter using firewall or WAF to restrict authentication attempts.
Strong password enforcement
allEnforce complex passwords (14+ characters, mixed case, numbers, symbols) for all accounts.
🧯 If You Can't Patch
- Isolate UCM6510 behind firewall with strict access controls, allowing only trusted IPs.
- Implement account lockout policies via external authentication system if supported.
🔍 How to Verify
Check if Vulnerable:
Check firmware version in web interface: System Status > Device Information. If version is 1.0.20.52 or lower, device is vulnerable.Check Version:
curl -k https://<device-ip>/cgi-bin/api-sys_operation?passcode=<passcode>&request=get_info | grep firmware_versionVerify Fix Applied:
After upgrade, verify version shows 1.0.20.53 or higher. Test authentication attempts - system should now limit failed attempts.📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts from same IP in short timeframe
- Successful login after many failures
Network Indicators:
- High volume of POST requests to /login or authentication endpoints
- Traffic patterns showing credential stuffing
SIEM Query:
source="ucm6510" AND (event_type="auth_failure" AND count > 10 within 5min)